chem3al_lab9

chem3al_lab9 - Chemistry 3AL 8 April 2011 Experiment #9...

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Chemistry 3AL 8 April 2011 Experiment #9 – What Do You Take for Pain? Discussion The acid-base chemistry used in this experiment involved a protonation of the naproxen ion. The naproxen in Aleve® exists as sodium naproxen; and will dissociate in water. The negative charge on the oxygen in the carboxylate group causes the naproxen ion to act as Bronsted base in this acid-base reaction with sulfuric acid. Sulfuric acid is a very strong acid, so it will immediately dissociate in an aqueous solution and will completely protonate the carboxylate group on the naproxen, resulting in a carboxylic acid. The naproxen ion is soluble in aqueous solution due to its negative charge, but once protonated, it is insoluble in cold water. Since the naproxen precipitates in cold water and that’s what will be recrystallized, sulfuric acid is added until we have a solution with pH of one to two to maximize the protonation of the naproxen ion. This co-solvent system is used because the compound to be purified must be soluble in one and insoluble in the other, and the solvents must be miscible. A single solvent wouldn’t work
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chem3al_lab9 - Chemistry 3AL 8 April 2011 Experiment #9...

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